1. Field of the Invention
The present invention relates to a status monitor and control system for use in a fiber optic communications system. In particular, the invention relates to a status monitoring system for a fiber optic CATV system, where the status monitoring system remotely monitors the operation of system components, provides information related to the performance of the system, and remotely controls certain operations of the system.
2. Description of the Related Art
Cable television operators have in the past utilized status monitoring systems to monitor the performance of outdoor pole mounted equipment. These monitoring systems have proven useful in isolating system faults. Conventional coaxial cable television systems are configured with a plurality of amplifiers connected in cascade along a coaxial RF transmission line. Due to the cascaded interconnections, failure in one amplifier causes a signal outage in all other amplifiers down the line. The monitoring systems transfer data using modulated frequency carriers to and from each amplifier station through the coaxial RF path. Accordingly, each amplifier station includes a forward path receiver and a reverse path transmitter. Additionally, data encoders and decoders are provided in the amplifier stations.
In recent years, there has been a great deal of interest in the transmission of video signals via optical fiber. This mode of signal transmission offers a number of advantages over transmitting signals over conventional 75 ohm coaxial cable as video signal distribution is now commonly accomplished in CATV systems. Optical fibers intrinsically have more information-carrying capacity than do coaxial cables. In addition, there is less signal attenuation in optical fibers than in coaxial cables adapted for carrying radio frequency signals. Consequently, optical fibers can span longer distances between signal regenerators than is possible with coaxial cable. In addition, the dielectric nature of optical fiber eliminates any problem with electrical shorting. Finally, optical fiber is immune to ambient electromagnetic interference (EMI) and generates no EMI of its own.
However, the monitoring systems for conventional cable systems are not adapted for use in monitoring fiber optic cable television systems due to inherent differences between the systems. For example, transmitter and receiver pairs in fiber systems serve large geographic areas. Intermediate amplifiers are not common. Therefore, loss in one fiber link is equivalent to loss of an entire coaxial trunk. Accordingly, it is extremely important that an operator be able to identify and isolate the cause of service outages. It is also important that an operator be made aware of warning signs which indicate the likelihood that a failure will occur.